From: Len Brown <[email protected]>
Linux suspend-to-RAM was unreliable when first developed,
and so sys_sync() was invoked inside the kernel at the
start of every suspend flow.
Today, many devices are invoking suspend with
high reliability and high frequency, and they don't
want to be forced to pay for sync on every suspend.
So here we make it optional.
De-select CONFIG_PM_SLEEP_SYNC to delete the call entirely.
or keep CONFIG_PM_SLEEP and you can now clear the
sys/power/sleep_sync attribte to disable the sync
from user-space.
As we have had this call for a long time,
the default remains to keep the call, and to
invoke it on every suspend.
Signed-off-by: Len Brown <[email protected]>
---
kernel/power/Kconfig | 8 ++++++++
kernel/power/main.c | 33 +++++++++++++++++++++++++++++++++
kernel/power/power.h | 1 +
kernel/power/suspend.c | 10 +++++++---
4 files changed, 49 insertions(+), 3 deletions(-)
diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
index 2fac9cc..d2927ce 100644
--- a/kernel/power/Kconfig
+++ b/kernel/power/Kconfig
@@ -102,6 +102,14 @@ config PM_SLEEP_SMP
depends on PM_SLEEP
select HOTPLUG_CPU
+config PM_SLEEP_SYNC
+ bool "Suspend to RAM starts with in-kernel call to sync()"
+ default y
+ depends on PM_SLEEP
+ ---help---
+ Build a call to sync() into the Linux kernel suspend to RAM flow.
+ The sync can still be skipped by clearing /sys/power/sleep_sync.
+
config PM_AUTOSLEEP
bool "Opportunistic sleep"
depends on PM_SLEEP
diff --git a/kernel/power/main.c b/kernel/power/main.c
index 1d1bf63..1102871 100644
--- a/kernel/power/main.c
+++ b/kernel/power/main.c
@@ -71,6 +71,36 @@ static ssize_t pm_async_store(struct kobject *kobj, struct kobj_attribute *attr,
power_attr(pm_async);
+#ifdef CONFIG_PM_SLEEP_SYNC
+
+/* If set, sync file systems at start of suspend flow */
+int pm_sleep_sync_enabled = 1;
+
+static ssize_t pm_sleep_sync_show(struct kobject *kobj, struct kobj_attribute *attr,
+ char *buf)
+{
+ return sprintf(buf, "%d\n", pm_sleep_sync_enabled);
+}
+
+static ssize_t pm_sleep_sync_store(struct kobject *kobj, struct kobj_attribute *attr,
+ const char *buf, size_t n)
+{
+ unsigned long val;
+
+ if (kstrtoul(buf, 10, &val))
+ return -EINVAL;
+
+ if (val > 1)
+ return -EINVAL;
+
+ pm_sleep_sync_enabled = val;
+ return n;
+}
+
+power_attr(pm_sleep_sync);
+
+#endif /* CONFIG_PM_SLEEP_SYNC */
+
#ifdef CONFIG_PM_DEBUG
int pm_test_level = TEST_NONE;
@@ -592,6 +622,9 @@ static struct attribute * g[] = {
#ifdef CONFIG_PM_SLEEP
&pm_async_attr.attr,
&wakeup_count_attr.attr,
+#ifdef CONFIG_PM_SLEEP_SYNC
+ &pm_sleep_sync_attr.attr,
+#endif
#ifdef CONFIG_PM_AUTOSLEEP
&autosleep_attr.attr,
#endif
diff --git a/kernel/power/power.h b/kernel/power/power.h
index 7d4b7ff..dca60a7 100644
--- a/kernel/power/power.h
+++ b/kernel/power/power.h
@@ -200,6 +200,7 @@ static inline void suspend_test_finish(const char *label) {}
#ifdef CONFIG_PM_SLEEP
/* kernel/power/main.c */
extern int pm_notifier_call_chain(unsigned long val);
+extern int pm_sleep_sync_enabled;
#endif
#ifdef CONFIG_HIGHMEM
diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
index 62ee437..2fb2f51 100644
--- a/kernel/power/suspend.c
+++ b/kernel/power/suspend.c
@@ -333,9 +333,13 @@ static int enter_state(suspend_state_t state)
if (state == PM_SUSPEND_FREEZE)
freeze_begin();
- printk(KERN_INFO "PM: Syncing filesystems ... ");
- sys_sync();
- printk("done.\n");
+#ifdef CONFIG_PM_SLEEP_SYNC
+ if (pm_sleep_sync_enabled) {
+ printk(KERN_INFO "PM: Syncing filesystems ... ");
+ sys_sync();
+ printk("done.\n");
+ }
+#endif /* CONFIG_PM_SLEEP_SYNC */
pr_debug("PM: Preparing system for %s sleep\n", pm_states[state]);
error = suspend_prepare(state);
--
1.8.3.2
On Thu, 2014-01-23 at 02:11 -0500, Len Brown wrote:
> From: Len Brown <[email protected]>
>
> Linux suspend-to-RAM was unreliable when first developed,
> and so sys_sync() was invoked inside the kernel at the
> start of every suspend flow.
>
> Today, many devices are invoking suspend with
> high reliability and high frequency, and they don't
> want to be forced to pay for sync on every suspend.
>
> So here we make it optional.
> De-select CONFIG_PM_SLEEP_SYNC to delete the call entirely.
> or keep CONFIG_PM_SLEEP and you can now clear the
> sys/power/sleep_sync attribte to disable the sync
> from user-space.
>
> As we have had this call for a long time,
> the default remains to keep the call, and to
> invoke it on every suspend.
>
> Signed-off-by: Len Brown <[email protected]>
> ---
> kernel/power/Kconfig | 8 ++++++++
> kernel/power/main.c | 33 +++++++++++++++++++++++++++++++++
> kernel/power/power.h | 1 +
> kernel/power/suspend.c | 10 +++++++---
> 4 files changed, 49 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
> index 2fac9cc..d2927ce 100644
> --- a/kernel/power/Kconfig
> +++ b/kernel/power/Kconfig
> @@ -102,6 +102,14 @@ config PM_SLEEP_SMP
> depends on PM_SLEEP
> select HOTPLUG_CPU
>
> +config PM_SLEEP_SYNC
> + bool "Suspend to RAM starts with in-kernel call to sync()"
> + default y
> + depends on PM_SLEEP
this is actually a suspend specific feature, and it should depends on
SUSPEND instead?
thanks,
rui
> + ---help---
> + Build a call to sync() into the Linux kernel suspend to RAM flow.
> + The sync can still be skipped by clearing /sys/power/sleep_sync.
> +
> config PM_AUTOSLEEP
> bool "Opportunistic sleep"
> depends on PM_SLEEP
> diff --git a/kernel/power/main.c b/kernel/power/main.c
> index 1d1bf63..1102871 100644
> --- a/kernel/power/main.c
> +++ b/kernel/power/main.c
> @@ -71,6 +71,36 @@ static ssize_t pm_async_store(struct kobject *kobj, struct kobj_attribute *attr,
>
> power_attr(pm_async);
>
> +#ifdef CONFIG_PM_SLEEP_SYNC
> +
> +/* If set, sync file systems at start of suspend flow */
> +int pm_sleep_sync_enabled = 1;
> +
> +static ssize_t pm_sleep_sync_show(struct kobject *kobj, struct kobj_attribute *attr,
> + char *buf)
> +{
> + return sprintf(buf, "%d\n", pm_sleep_sync_enabled);
> +}
> +
> +static ssize_t pm_sleep_sync_store(struct kobject *kobj, struct kobj_attribute *attr,
> + const char *buf, size_t n)
> +{
> + unsigned long val;
> +
> + if (kstrtoul(buf, 10, &val))
> + return -EINVAL;
> +
> + if (val > 1)
> + return -EINVAL;
> +
> + pm_sleep_sync_enabled = val;
> + return n;
> +}
> +
> +power_attr(pm_sleep_sync);
> +
> +#endif /* CONFIG_PM_SLEEP_SYNC */
> +
> #ifdef CONFIG_PM_DEBUG
> int pm_test_level = TEST_NONE;
>
> @@ -592,6 +622,9 @@ static struct attribute * g[] = {
> #ifdef CONFIG_PM_SLEEP
> &pm_async_attr.attr,
> &wakeup_count_attr.attr,
> +#ifdef CONFIG_PM_SLEEP_SYNC
> + &pm_sleep_sync_attr.attr,
> +#endif
> #ifdef CONFIG_PM_AUTOSLEEP
> &autosleep_attr.attr,
> #endif
> diff --git a/kernel/power/power.h b/kernel/power/power.h
> index 7d4b7ff..dca60a7 100644
> --- a/kernel/power/power.h
> +++ b/kernel/power/power.h
> @@ -200,6 +200,7 @@ static inline void suspend_test_finish(const char *label) {}
> #ifdef CONFIG_PM_SLEEP
> /* kernel/power/main.c */
> extern int pm_notifier_call_chain(unsigned long val);
> +extern int pm_sleep_sync_enabled;
> #endif
>
> #ifdef CONFIG_HIGHMEM
> diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
> index 62ee437..2fb2f51 100644
> --- a/kernel/power/suspend.c
> +++ b/kernel/power/suspend.c
> @@ -333,9 +333,13 @@ static int enter_state(suspend_state_t state)
> if (state == PM_SUSPEND_FREEZE)
> freeze_begin();
>
> - printk(KERN_INFO "PM: Syncing filesystems ... ");
> - sys_sync();
> - printk("done.\n");
> +#ifdef CONFIG_PM_SLEEP_SYNC
> + if (pm_sleep_sync_enabled) {
> + printk(KERN_INFO "PM: Syncing filesystems ... ");
> + sys_sync();
> + printk("done.\n");
> + }
> +#endif /* CONFIG_PM_SLEEP_SYNC */
>
> pr_debug("PM: Preparing system for %s sleep\n", pm_states[state]);
> error = suspend_prepare(state);
> > + depends on PM_SLEEP
>
> this is actually a suspend specific feature, and it should depends on
> SUSPEND instead?
yup, will update.
thanks,
-Len
????{.n?+???????+%?????ݶ??w??{.n?+????{??G?????{ay? ʇڙ?,j??f???h?????????z_??(?階?ݢj"???m??????G????????????&???~???iO???z??v?^?m???? ????????I?
On 01/23/2014 12:41 PM, Len Brown wrote:
> From: Len Brown <[email protected]>
>
> Linux suspend-to-RAM was unreliable when first developed,
> and so sys_sync() was invoked inside the kernel at the
> start of every suspend flow.
>
> Today, many devices are invoking suspend with
> high reliability and high frequency, and they don't
> want to be forced to pay for sync on every suspend.
>
> So here we make it optional.
> De-select CONFIG_PM_SLEEP_SYNC to delete the call entirely.
> or keep CONFIG_PM_SLEEP and you can now clear the
> sys/power/sleep_sync attribte to disable the sync
> from user-space.
>
> As we have had this call for a long time,
> the default remains to keep the call, and to
> invoke it on every suspend.
>
> Signed-off-by: Len Brown <[email protected]>
> ---
> kernel/power/Kconfig | 8 ++++++++
> kernel/power/main.c | 33 +++++++++++++++++++++++++++++++++
> kernel/power/power.h | 1 +
> kernel/power/suspend.c | 10 +++++++---
> 4 files changed, 49 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
> index 2fac9cc..d2927ce 100644
> --- a/kernel/power/Kconfig
> +++ b/kernel/power/Kconfig
> @@ -102,6 +102,14 @@ config PM_SLEEP_SMP
> depends on PM_SLEEP
> select HOTPLUG_CPU
>
> +config PM_SLEEP_SYNC
How about naming it as PM_SLEEP_FS_SYNC (and similarly in the sysfs files
and variable names as well). Just to avoid confusion with "synchronous/async".
Regards,
Srivatsa S. Bhat
> + bool "Suspend to RAM starts with in-kernel call to sync()"
> + default y
> + depends on PM_SLEEP
> + ---help---
> + Build a call to sync() into the Linux kernel suspend to RAM flow.
> + The sync can still be skipped by clearing /sys/power/sleep_sync.
> +
> config PM_AUTOSLEEP
> bool "Opportunistic sleep"
> depends on PM_SLEEP
> diff --git a/kernel/power/main.c b/kernel/power/main.c
> index 1d1bf63..1102871 100644
> --- a/kernel/power/main.c
> +++ b/kernel/power/main.c
> @@ -71,6 +71,36 @@ static ssize_t pm_async_store(struct kobject *kobj, struct kobj_attribute *attr,
>
> power_attr(pm_async);
>
> +#ifdef CONFIG_PM_SLEEP_SYNC
> +
> +/* If set, sync file systems at start of suspend flow */
> +int pm_sleep_sync_enabled = 1;
> +
> +static ssize_t pm_sleep_sync_show(struct kobject *kobj, struct kobj_attribute *attr,
> + char *buf)
> +{
> + return sprintf(buf, "%d\n", pm_sleep_sync_enabled);
> +}
> +
> +static ssize_t pm_sleep_sync_store(struct kobject *kobj, struct kobj_attribute *attr,
> + const char *buf, size_t n)
> +{
> + unsigned long val;
> +
> + if (kstrtoul(buf, 10, &val))
> + return -EINVAL;
> +
> + if (val > 1)
> + return -EINVAL;
> +
> + pm_sleep_sync_enabled = val;
> + return n;
> +}
> +
> +power_attr(pm_sleep_sync);
> +
> +#endif /* CONFIG_PM_SLEEP_SYNC */
> +
> #ifdef CONFIG_PM_DEBUG
> int pm_test_level = TEST_NONE;
>
> @@ -592,6 +622,9 @@ static struct attribute * g[] = {
> #ifdef CONFIG_PM_SLEEP
> &pm_async_attr.attr,
> &wakeup_count_attr.attr,
> +#ifdef CONFIG_PM_SLEEP_SYNC
> + &pm_sleep_sync_attr.attr,
> +#endif
> #ifdef CONFIG_PM_AUTOSLEEP
> &autosleep_attr.attr,
> #endif
> diff --git a/kernel/power/power.h b/kernel/power/power.h
> index 7d4b7ff..dca60a7 100644
> --- a/kernel/power/power.h
> +++ b/kernel/power/power.h
> @@ -200,6 +200,7 @@ static inline void suspend_test_finish(const char *label) {}
> #ifdef CONFIG_PM_SLEEP
> /* kernel/power/main.c */
> extern int pm_notifier_call_chain(unsigned long val);
> +extern int pm_sleep_sync_enabled;
> #endif
>
> #ifdef CONFIG_HIGHMEM
> diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
> index 62ee437..2fb2f51 100644
> --- a/kernel/power/suspend.c
> +++ b/kernel/power/suspend.c
> @@ -333,9 +333,13 @@ static int enter_state(suspend_state_t state)
> if (state == PM_SUSPEND_FREEZE)
> freeze_begin();
>
> - printk(KERN_INFO "PM: Syncing filesystems ... ");
> - sys_sync();
> - printk("done.\n");
> +#ifdef CONFIG_PM_SLEEP_SYNC
> + if (pm_sleep_sync_enabled) {
> + printk(KERN_INFO "PM: Syncing filesystems ... ");
> + sys_sync();
> + printk("done.\n");
> + }
> +#endif /* CONFIG_PM_SLEEP_SYNC */
>
> pr_debug("PM: Preparing system for %s sleep\n", pm_states[state]);
> error = suspend_prepare(state);
>
> How about naming it as PM_SLEEP_FS_SYNC (and similarly in the sysfs
> files
> and variable names as well). Just to avoid confusion with
> "synchronous/async".
good point -- thanks!
Hi!
> From: Len Brown <[email protected]>
>
> Linux suspend-to-RAM was unreliable when first developed,
> and so sys_sync() was invoked inside the kernel at the
> start of every suspend flow.
>
> Today, many devices are invoking suspend with
> high reliability and high frequency, and they don't
> want to be forced to pay for sync on every suspend.
>
> So here we make it optional.
> De-select CONFIG_PM_SLEEP_SYNC to delete the call entirely.
> or keep CONFIG_PM_SLEEP and you can now clear the
> sys/power/sleep_sync attribte to disable the sync
> from user-space.
Dunno. Config option plus sysfs attribute is overdoing it a bit.
Maybe we could do
echo memfast > state
to enter suspend without sync? Patch should be simpler that way,
and we won't have to keep the state...
Pavel
On Sun, Jan 26, 2014 at 4:08 PM, Pavel Machek <[email protected]> wrote:
> Dunno. Config option plus sysfs attribute is overdoing it a bit.
Agreed.
Have discussed w/ Rafael, and current plan is to simply delete.
Updated patch on the way...
thanks,
Len Brown, Intel Open Source Technology Center